The present invention relates to a new and distinctive pearl millet line, designated 53-1-1. The term “millet” is applied to various grassy crops whose seeds are harvested for human food or animal feed. Compared to other cereal grains, millets are generally suited to less fertile soils and poorer growing conditions, such as intense heat and low rainfall and shorter growing seasons.
There are five genera of millets, Panicum, Setaria, Echinochloa, Pennisetum, and Paspalum, all of the tribe Paniceae; one genus, Eleusine, in the tribe Chlorideae; and one genus, Eragrostis, in the tribe Festuceae. The most important cultivated species of millet are foxtail (Setaria italica), pearl or cattail millet (Pennisetum glaucum), proso (Panicum miliaceum), Japanese barnyard millet (Echinochola crusgalli), finger millet (Eleusine coracana), browntop millet (Panicum ramosum), koda or ditch millet (Paspalum scrobiculatum), and teff millet (Eragrostis tef).
The present invention relates to Pennisetum glaucum (L) R&BR, commonly known as pearl millet. Pearl millet, a cross-pollinating diploid (2n=14), is one of about 140 Pennisetum species worldwide which differ in both chromosome number (5, 7, 8 or 9) and ploidy level. The pearl millet gene pool is limited to cultivated pearl millet—Pennisetum glaucum ssp glaucum; polymorphic wild pearl millet—Pennisetum glaucum ssp monodii (from which cultivated varieties were domesticated), and the resultant weedy intermediate populations—Pennisetum glaucum ssp stenostachyum. Pearl millet will also cross naturally with elephant grass, Pennisetum purpureum (Schum.), a tetraploid (2n=28), but the resulting hybrids being triploid are sterile. Pearl millet will not naturally hybridize with other millet species but hybrids have been made artificially with several Pennisetum species, however these have all been reproductively defective.
Pearl millet originated in sub-saharan west Africa and is principally grown as a food grain in Africa and southeast Asia, mainly India, with crop residues used as forage, fuel and construction. It is also grown principally for forage in Brazil, the USA and Australia and dwarf grain hybrids have potential as feed grain for poultry. West African land race cultivars range from 35 to 140 days to flowering and from 1.5 to 5.0 m tall. 1 to 5 basal tillers bear dense cylindrical spikes from 20 cm to 2 m long. Globose to cylindrical grains are 2 to 4 mm long and weigh 5 to 20 g./1000. Short duration cultivars can successfully mature in warm temperate summers as far as 50_ from the equator provided there sufficient days above 10_C. (60_F). Pearl millet is not frost tolerant.
Pearl millet cultivars are either varieties (stable heterozygous intermating populations) or F1 hybrids usually made from inbred parental lines. New varieties are usually produced by population breeding (for example recurrent selection), and parental lines by pedigree (for example head to row) breeding.
Single cross hybrids (F1 plants resulting from crossing two inbred lines) represent the most practical genotype to consistently deliver productivity and quality. Such hybrids have utility in pearl millet. The breeding of parental lines that which, in combination will contribute productivity and specific desired qualities to a hybrid is a lengthy breeding process. This requires the generation of appropriate genetic variability from which inbred lines with new recombinations of desired traits can be obtained through selection procedures and combining ability tests. Separate breeding streams are required for male and female parents.
Pearl millet is a wind cross pollinated diploid species where all flowers on a head are perfect (most flowers contain functional male and female parts). Thus, to produce 100% hybrid seed, one parental line should be male sterile (female fertile only) which will ensure that all seed set on that line will be hybrid seed resulting from pollination by the other normally male fertile parent (provided other pollen sources are excluded). In pearl millet the production of all male sterile plants in quantity is achieved by the use of a cytoplasmic—nuclear male sterility (CMS) system, of which there are several, the most useful being A1 (the original), A4 and A5.
To repeatedly reproduce seed of a CMS male sterile line involves the use of the same nuclear genome in two different cytoplasm types (cytoplasm is normally only maternally inherited, and carries non-nuclear genes which rarely change). The cytoplasm type where a line is normally both male and female fertile is designated “normal”. When pollen from this line, which carries haploid set of nuclear genes, but (normally) no cytoplasm, pollinates a plant which is CMS male sterile (and therefore is said to have “sterile”[inducing] cytoplasm) but female fertile, the progeny from this cross may be of several types in regard to male fertility (fertile pollen):                a) All male sterile.        b) all partially male fertile.        c) segregate for plants that are completely male fertile, or completely male sterile.        d) All fully male fertile.        e) A mix of some or all the above.        
When the progeny are all male sterile, (case a) the pollen donor line is classified as a maintainer line (designated a B-line by convention), in respect of that particular CMS system, since it maintained the state of male sterility. This line can be used to make an iso-nuclear male sterile seed parent (below).
If on the other hand, the progeny are all male fertile, (case d) then the pollen donor line is said to be a restorer (by convention an R-line) in respect of that CMS system, since it restored male fertility. Restorer lines can be used directly as male parents to make hybrids in that CMS system. R lines carry nuclear genes for male fertility that tend to be dominant and are usually specific to a CMS system. One line can be R in respect of one system and B in another.
Cases b) and e) show the pollen donor line has little utility to become a hybrid parent on that CMS system. Case c) indicates that the pollen donor line is still segregating for these factors and either a B or an R line could be produced by further selection and test crossing.
By repeated back crossing using pollen from the B-line starting with the male sterile F1 (case a), the nuclear genome of the B line can effectively replace the nuclear genome of the line donating the (male) sterile inducing cytoplasm. The resulting male sterile line, which is then of the same nuclear constitution of the B line but in sterile cytoplasm, is by convention called an A line, also known as a seed parent. More A line seed can be increased by pollination with the B line. Pure seed of a hybrid which will be male fertile can then be produced in quantity by pollinating sufficient A line plants with R line pollen in isolation from other sources of pollen. Or, if it is desirable, a male sterile hybrid can be produced by crossing an A-line with a non-restoring line (in effect another B line) of a different and complementary nuclear constitution.
Red or purple plant pigmentation, due to the presence of anthocyanins, occurs naturally in pearl millet germplasm, either on specific plant parts or more generally over the plant. In the latter case, young plants appear normal green until 20-30 days old (the juvenile growth phase) when pigmentation on leaf blades becomes progressively more evident. However, on all seedlings of prior cultivars that later have general red or purple coloration, traces of this coloration develop as early as five days after emergence on leaf margins but not before 10 days on the keel of the first leaf midrib.